The present invention relates to an injection material for use in the hot repairing of a furnace wall of a blast furnace and a method of applying the same under pressure, in particular to an injection material superior in low-temperature hardenability and durability for use in a relatively low temperature portion, such as a space between water cooled panels or between stave-coolers of the blast furnace, and an injection method of applying the same.
The repairing of a blast furnace is remarkably important in respect to not only the prolongation of the life but also the stable operation of the blast furnace and the injection repairing of the blast furnace has been carried out during the suspension of the blast operation, a repairing material containing binder, such as sodium silicate, has been used as an injection material. However, this sodium silicate injection material is not a durable binder due to the poor adhesion of sodium silicate to carbon-bonded bricks and is especially ineffective under severe operating conditions of the blast to furnace carbonaceous injection materials using tar, pitch or various kinds of resin as a binder have been increasingly used.
The temperature of the space between water cooled panels or between stave-coolers, is further reduced during the suspension of blast operation, so that an injection material using tar or pitch as a binder has never exhibited a sufficient adhesion to the furnace wall and a sufficient hardening in a short time until the restart of the operation. As a result, it has never exhibited a satisfactory durability.
Thus, a low temperature hardening material using thermoplastic phenolic resins as a binder, and hexamethylenetetramine as a hardening agent, or a material using thermosetting phenolic resins or furan resins together with p-toluenesulfonic acid have been proposed.
However, the material using thermoplastic phenolic resins together with hexamethylenetetramine as a hardening agent has a disadvantage in that the hardening proceeds at temperature in the range of the decomposition temperature of the hexamethylenetetramine or higher, for example, at temperatures of 150.degree. C. or higher, however sufficient hardening does not proceed at such temperatures.
On the other hand, with a material using thermosetting phenolic resins or furan resins together with p-toluenesulfonic acid, not only does the hardening proceed even at room temperature, but also the hardening speed can be adjusted by changing the quantity of organic acid added. However, this material also has never exhibited a sufficient durability in the use thereof in a practical furnace. A reason for this seems to be that once the reaction starts, it proceeds with increasing speed since the hardening by the use of organic acids is an exothermic reaction, whereby the resulting repaired body is high in porosity and inferior in physical properties. Moreover since the atmosphere within the blast furnace is highly alkaline, an acid used as the hardening agent reacts with the alkaline atmosphere, whereby the repaired body is made deteriorated.
On the other hand, as to the repairing, in the case where the repairing material is hardened at high temperatures, all materials including the hardening agent can be mixed in the factory and the mixed material is simply injected by means of an injection apparatus in the working area. However, in the case where the injection repairing is carried out by the use of materials hardening at low temperatures, the reaction by the hardening agent starts at the time when all ingredients and a wetting agent are mixed to form a slurry, so that it is impossible to mix the materials 2 to 10 days before repairing a furnace.
Although the above problem can be overcome by simply adding the hardening agent and mixing the ingredients in the working area, in the case where the hardening agent is added and mixed, a large amount, for example, 1 to 2 tons, of injection material must be mixed at a time in a large-sized mixer in order to efficiently mix with the binder and the hardening agent. However, it is more preferable to inject a small amount, such as 100 to 300 kg, of the injection material in the furnace through a large number of openings than to inject a large amount of the injection material through only one opening in view of the repairing of a wide range within the furnace. Accordingly, it takes 2 to 3 hours from the completion of the mixing till the completion of the working, so that if the mixing is carried out at a time, the materials are hardened in the hose used to transport the materials, thereby making the transportation of the repairing material impossible.
In addition, the temperature of a blast furnace side wall is not constant throughout due to the variety of the thickness of the remaining bricks, varying operating conditions and the like. It is desirable that the injection material has an appropriate hardening speed but it is impossible in the case wherein the materials harden quickly as discussed above.
Even if the amount of the injection material necessary for injection to one opening is mixed, it takes about one hour to charge the materials in a hopper and inject the resulting repairing material in the portion to be repaired, so that a large amount of injections can not be performed during the suspension of the blast operation.
In this time, although the hardening time can be increased by reducing the quantity of the hardening agent, a small amount of the hardening agent can not achieve the desired object for repair in the case where a temperature of the portion to be injected is low.
In view of the above, a method, in which a hardening agent is poured into refractory materials by means of a nozzle, has also been proposed (Japanese Patent Publication No. 56-1363). However, with this method, since the mixing is insufficient, the stable repair can not be achieved. In addition, considerable hands are required for the parallel operation of injection pumps and the like, so that this method is practically unsuitable.